Innovative method to build a high precision analog capacitor with low voltage coefficient and hysteresis

ABSTRACT

The present invention relates to a method for forming an anlog capacitor on a semiconductor substrate. The method comprises forming a field oxide over a portion of the substrate, and forming a polysilicon layer over the field oxide layer, and subsequently forming a silicide over the polysilicon layer. A first interlayer dielectric layer is formed over the substrate, and a capacitor masking pattern is formed. The first interlayer dielectric is etched using the capacitor masking pattern as a mask and the silicide layer as an etch stop, and a thin dielectric is formed over the substrate. A contact masking pattern is formed over the substrate, and a subsequent etch is performed on the thin dielectric and the first interlayer dielectric using the silicide and substrate as an etch stop. A metal layer is deposited over the substrate, and is subsequently planarized, thereby defining an analog capacitor.

TECHNICAL FIELD OF INVENTION

The present invention relates generally to integrated circuits, and moreparticularly, to a method of forming a high precision analog capacitorfor use in an integrated circuit.

BACKGROUND OF THE INVENTION

The manufacturing of semiconductor devices is a combination of thecreation of a variety of components that collectively perform functionsof data manipulation (logic functions) and of data retention (storagefunctions). The vast majority of these functions operate in a digital oron/off mode, and as such, recognizes “zero” and “one” conditions withinthe operational levels of the circuits. There are, in addition,applications that make use of analog levels of voltage, for example,wherein the voltage may have a spectrum of values between a high limitand a low limit. Furthermore, applications exist where both digital andanalog methods of signal processing reside in the same semiconductordevice.

A mixture of functions and processing capabilities brings with it amixture of components that can co-exist within one semiconductor device.Where the vast majority of device components is made up of transistorsand a variety of switching components that address logic processingfunctions, it is not uncommon to also see resistors and capacitors thatform part of a semiconductor device. For instance, it is known thatcapacitors form a basic component of many analog circuits that are usedfor analog applications such as analog-to-digital and digital-to-analogdata conversion. Besides A/D conversion, capacitors perform a variety ofcritical tasks required to interface digital data with the externalworld, such as amplification, pre-filtering demodulation and signalconditioning. It is also well known in the art that capacitors arewidely applied in digital applications such as the storage node forDynamic Random Access Memory (DRAM) circuits. In general, an analogcapacitor stores information in various states, whereas a digitalcapacitor stores information in two states, namely, low and high.Typical analog applications involve analog-to-digital ordigital-to-analog data conversion. Beside data conversion

In reference to the manufacture of analog capacitors, FIG. 1Aillustrates a cross-sectional view 100 of a conventional analogcapacitor 105, and FIG. 1B illustrates a conventional method 150 offabrication of said capacitor. One of the first processing steps that isrequired in forming the capacitor 105 on the surface of a semiconductorsubstrate 110 is to electrically isolate the active regions (the regionswhere transistor devices will be created) on the surface of thesubstrate. Act 160 of FIG. 1B isolates the device 105 from other devices(not shown) on the semiconductor substrate 110 by forming a field oxide(F_(OX)) 115. One conventional approach in the semiconductor industryfor forming the F_(OX) 115 is by the Local Oxidation of Silicon (LOCOS)method. LOCOS typically uses a patterned silicon nitride (Si₃N₄) layer(not shown) as an oxidation barrier mask, wherein the underlying siliconsubstrate 110 is selectively oxidized. One disadvantage of utilizingLOCOS is that a non-planar surface of the semiconductor substrateresults. Another method of forming the field oxide (F_(OX)) is toutilize Shallow Trench Isolation (STI) (not shown). One method ofutilizing STI is to first etch trenches (not shown) having essentiallyvertical sidewalls in the silicon substrate. The trenches are typicallythen filled with a Chemical Vapor Deposition (CVD) of silicon oxide(SiO₂) and the silicon oxide is then plasma etched or planarized usingCMP to form an STI region which is significantly planar.

Following the formation of the F_(OX) 115, a polysilicon layer 120 isformed over the F_(OX) 115 in act 162 of FIG. 1B to define a bottomplate 121 of a capacitor 105. A silicide layer 125 is subsequentlyformed over the polysilicon layer 120 in act 164 to form a conductiveetch stop over the polysilicon layer. The formation of the polysiliconlayer 120 typically forms a vertical step 127 on the surface of thesubstrate 110. Unfortunately, this vertical step 127 results indeleterious effects when forming the capacitor 105 in the prior art, aswill be described hereafter.

Subsequent to forming the polysilicon layer 120 and silicide layer 125,an oxide layer 130 is blanket deposited over the substrate in act 166 ofFIG. 1B, typically by Low Pressure Chemical Vapor Deposition (LPCVD) toform a dielectric layer for the capacitor 105. A titanium nitride (TiN)layer 135 is then deposited over the substrate 110 in act 168 of FIG.1B. A titanium nitride (TiN) hard mask layer 137 which is selective withrespect to the underlying TiN layer 135 is furthermore formed over theTiN layer 135 in act 170. A capacitor masking pattern (not shown) isformed in act 172, whereby a subsequent hard mask etch and TiN etch areperformed in act 174, thereby removing portions of the TiN hard masklayer 137 and TiN layer 135 to define a top plate 140 of the capacitor105.

Following the TiN etch of act 174, an Interlayer Dielectric (ILD) layer142 is formed by conventional methods. A contact masking pattern (notshown) is formed over the ILD layer 142 in act 178 of the prior art, andthe ILD layer is etched in act 180 to form contact holes 143. A metal144 is deposited over the ILD layer 142 in act 182, thereby filling thecontact holes 143, and the metal is subsequently planarized in act 184.A wiring layer 145 in then formed over the contact holes 143 tointerconnect the capacitor 105 to other devices (not shown) on thesemiconductor substrate 110.

Due to the prior art method 150 utilizing a TiN layer 135 for a topplate 140 of the capacitor 105, the TiN etching performed in act 174 iscritical, since the etch must stop at the semiconductor substrate 110 inorder to avoid pitting of the semiconductor substrate. The etch mustalso be sufficient enough, however, to remove the TiN layer 135 residingover the silicide layer 125 in order to avoid stringers, (i.e.,un-etched TiN residing on the suicide layer), which could potentiallycause leakage in operation of the capacitor 105. Accordingly, the TiNetch process of act 174 must be monitored closely in order to avoid thedeleterious effects of both over-etching into the semiconductorsubstrate 110 as well as under-etching the TiN layer 135. Furthermore,the step 127 of FIG. 1A caused by the formation of the polysilicon layer120 over a non-planar surface of the substrate 110 accentuates thedifficulty of the TiN etch when LOCOS is utilized in forming the F_(OX).

SUMMARY OF THE INVENTION

The following presents a simplified summary of the invention in order toprovide a basic understanding of some aspects of the invention. Thissummary is not an extensive overview of the invention. It is intended toneither identify key or critical elements of the invention nor delineatethe scope of the invention. Its purpose is to present some concepts ofthe invention in a simplified form as a prelude to the more detaileddescription that is presented later.

The present invention relates generally to a method of forming an analogcapacitor on a semiconductor substrate. More particularly, the inventionrelates to a method of forming a high precision analog capacitor over afield oxide (F_(OX)) on a semiconductor substrate. According to thepresent invention, a field oxide layer is formed over a portion of thesubstrate. A polysilicon layer is formed over the field oxide layer,thereby defining a bottom plate of the capacitor, and a silicide isformed over the polysilicon layer, thereby defining a bottom plate ofthe capacitor. A first interlayer dielectric (ILD) layer is then formedover the substrate. According to one exemplary aspect of the invention,the first ILD layer comprises a plurality of layers.

Following the formation of the first ILD layer, a capacitor maskingpattern is formed over the substrate, and an etching process isperformed, wherein the first interlayer dielectric is etched using thecapacitor masking pattern as a mask and the silicide as an etch stop,thereby defining a capacitor region. A thin dielectric is then formedover the substrate. According to another exemplary aspect of the presentinvention, the thin dielectric is formed by a low pressure chemicalvapor deposition (LPCVD) process.

A contact masking pattern having one or more contact holes is formedover the substrate following the formation of the thin dielectric, andanother etch process is performed, wherein the thin dielectric and thefirst interlayer dielectric are etched using the contact masking patternas a mask and the silicide as an etch stop. According to yet anotherexemplary aspect of the invention, the contact masking pattern comprisesa bottom plate capacitor contact hole and a moat contact hole, whereinthe etching the thin dielectric and the first ILD layer comprises usingthe silicide as an etch stop for the bottom plate capacitor contact holeand the semiconductor substrate as an etch stop for the moat contacthole.

A metal layer is subsequently formed over the substrate, wherein themetal layer substantially fills the one or more contact holes.Furthermore, the metal layer is planarized, wherein a top plate of thecapacitor and an electrical connection to the bottom plate of thecapacitor are defined, and wherein the top plate of the capacitor andthe electrical connection to the bottom plate of the capacitor arelaterally isolated by the first ILD.

To the accomplishment of the foregoing and related ends, the inventioncomprises the features hereinafter fully described and particularlypointed out in the claims. The following description and the annexeddrawings set forth in detail certain illustrative embodiments of theinvention. These embodiments are indicative, however, of but a few ofthe various ways in which the principles of the invention may beemployed. Other objects, advantages and novel features of the inventionwill become apparent from the following detailed description of theinvention when considered in conjunction with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A illustrates a partial cross-sectional view of a conventionalanalog capacitor formed according to a method of the prior art.

FIG. 1B illustrates a method for forming a conventional analog capacitoraccording to the prior art.

FIG. 2A illustrates a method for forming an analog capacitor accordingto the present invention.

FIG. 2B illustrates a method for forming an analog capacitor accordingto one aspect of the present invention.

FIG. 3 illustrates a partial cross-sectional view of a step of forming afield oxide and polysilicon layer for an analog capacitor according tothe present invention.

FIG. 4 illustrates a partial cross-sectional view of a step of forming afirst interlayer dielectric layer for an analog capacitor according tothe present invention.

FIG. 5 illustrates a partial cross-sectional view of a step of formingfirst interlayer dielectric (ILD) layer for an analog capacitoraccording to one aspect of the present invention.

FIG. 6 illustrates a partial cross-sectional view of a step of forming acapacitor masking pattern for an analog capacitor according to thepresent invention.

FIG. 7 illustrates a partial cross-sectional view of a step of etchingthe first ILD layer for an analog capacitor according to the presentinvention.

FIG. 8 illustrates a partial cross-sectional view of a step of forming athin dielectric layer for an analog capacitor according to the presentinvention.

FIG. 9 illustrates a partial cross-sectional view of a step of forming acontact masking pattern for an analog capacitor according to the presentinvention.

FIG. 10 illustrates a partial cross-sectional view of a step of etchingthe thin dielectric and first ILD layer for an analog capacitoraccording to the present invention.

FIG. 11 illustrates a partial cross-sectional view of a step of forminga metal layer for an analog capacitor according to the presentinvention.

FIG. 12 illustrates a partial cross-sectional view of a step ofplanarizing the first metal layer for an analog capacitor according tothe present invention.

FIG. 13 illustrates a partial cross-sectional view of a step of forminga conductive connecting layer for an analog capacitor according to thepresent invention.

DETAILED DESCRIPTION OF THE INVENTION

The present invention will now be described with reference to thedrawings wherein like reference numerals are used to refer to likeelements throughout. It should be understood that the description ofthese aspects are merely illustrative and that they should not be takenin a limiting sense. In the following description, for purposes ofexplanation, numerous specific details are set forth in order to providea thorough understanding of the present invention. It will be evident toone skilled in the art, however, that the present invention may bepracticed without these specific details.

The terms “wafer” and “substrate” are to be understood as includingsilicon-on-insulator (SOI) or silicon-on-sapphire (SOS) technology,doped and undoped semiconductors, epitaxial layers of silicon supportedby a base semiconductor foundation, and other semiconductor structures.Furthermore, when reference is made to a “wafer” or “substrate” in thefollowing description, previous process steps may have been utilized toform regions or junctions in the base semiconductor structure orfoundation. In addition, the semiconductor need not be silicon-based,but could be based on, for example, silicon-germanium, germanium, orgallium arsenide.

The present invention is directed toward a method for forming an analogcapacitor over a semiconductor substrate. While exemplary methods areillustrated and described herein as a series of acts or events, it willbe appreciated that the present invention is not limited by theillustrated ordering of such acts or events, as some steps may occur indifferent orders and/or concurrently with other steps apart from thatshown and described herein, in accordance with the invention. Inaddition, not all illustrated steps may be required to implement amethodology in accordance with the present invention. Moreover, it willbe appreciated that the methods may be implemented in association withthe apparatus and systems illustrated and described herein as well as inassociation with other systems not illustrated.

Referring now to FIG. 2A, a method 200 of forming an analog capacitor ona semiconductor substrate according to one aspect of the presentinvention will be described. The method 200 begins with act 205, whereina field oxide (F_(OX)) is formed over the semiconductor substrate,thereby defining active regions (e.g., the regions where semiconductordevices will be created). The active regions are furthermoreelectrically isolated on the substrate surface by the field oxide. Across-sectional view 300 of an exemplary semiconductor substrate 301 isillustrated in FIG. 3, wherein a field oxide 305 is formed over thesemiconductor substrate by a Local Oxidation of Silicon (LOCOS) method.Alternatively, a Shallow Trench Isolation (STI) method may be utilizedto form the field oxide 305, however, any method of forming an isolatedfield oxide over the semiconductor substrate 301 is contemplated asfalling within the scope of the present invention.

Following the formation of the field oxide 305, a polysilicon layer 310is formed over the field oxide in act 210 of FIG. 2A. As illustrated inFIG. 3, the polysilicon layer 310, for example, can be blanket depositedover the substrate 301 and patterned by conventional lithography andetching techniques. The polysilicon layer 310 which remains afteretching thereby defines a bottom plate 314 of a capacitor. After thepolysilicon layer 310 is formed over the field oxide 305 in act 210, asilicide layer 315 is formed over the polysilicon layer in act 215 ofFIG. 2A. As will be understood by one of ordinary skill in the art, thesilicide layer 315 of FIG. 3 may be formed by a metal deposition andthermal treatment of the substrate 301.

FIG. 4 illustrates a first Interlayer Dielectric (ILD) layer 320 (e.g.,an oxide layer) which is formed over the semiconductor substrate 301 inact 220 of FIG. 2A. According to one exemplary aspect of the presentinvention, the ILD layer 320 comprises a plurality of layers. Forexample, the ILD layer 320 can comprise one or more ofborophosphosilicate glass (BPSG), phosphosilicate glass (PSG), undopedsilicate glass (USG), borosilicate glass (BSG), tetraethylorthosilicate(TEOS), undoped silicon dioxide, or the like. According to one exemplaryaspect of the present invention, the first ILD layer 320 is formed to athickness of about 10 kÅ. According to a preferred embodiment of thepresent invention, the first ILD layer 320 is formed according to theacts illustrated in FIG. 2B, beginning with act 221, forming a first USGlayer. FIG. 4 illustrates a first USG layer 322 formed over thesubstrate 301. As will be understood by one of ordinary skill in theart, the first USG layer 322 is formed to significantly preventmigration of dopants such as phosphorus from PSG or phosphorus and boronfrom BPSG of the ILD layer 320 to the polysilicon layer 310 or siliconlayer 301. Following the formation of the first USG layer 322, a PSGlayer 323 is formed in act 222 of FIG. 2B, and the USG layer and PSGlayer are subsequently densified in act 223. The densification performedin act 223 may be accomplished by thermal flow processes, as will beunderstood by one of ordinary skill in the art. Densification isperformed to generally reduce the viscosity of ILD layer 320, therebygenerally stabilizing the ILD layer.

Following the densification illustrated in act 223, a planarization ofthe PSG layer 323 of FIG. 4 is performed. The planarization of the PSGlayer 323 can be performed, for example, by a Chemical MechanicalPolishing (CMP) process. As will be understood by one of ordinary skillin the art, CMP is accomplished by using a combination of chemicaletching and mechanical abrasion, wherein a slurry is typically appliedto the surface of a rotating platen or polishing head (not shown) tosignificantly planarize the PSG layer 323.

After the planarization of the PSG layer 323 in act 224 of FIG. 2B, asecond USG layer is formed over the substrate in act 225. FIG. 5illustrates the second USG layer 324 formed over the PSG layer 323, thuscompleting the formation of the multi-layered first ILD layer 320. Thesecond USG layer 324 may, for example, comprise tetraethylorthosilicate(TEOS) to block phosphorus diffusion between the PSG layer 323 and asubsequently formed metal layer (not shown). For purposes of clarity,the PSG layer 323 and the second USG layer 324 will be illustratedhereafter as the ILD layer 320 as illustrated in FIG. 6, however, theILD layer 320 will be understood to comprise any interlayer dielectriclayer.

Referring again to FIG. 2A, following the formation of the ILD layer 320in act 220, a capacitor masking pattern is formed in act 230. FIG. 6illustrates an exemplary capacitor masking pattern 325, wherein thecapacitor masking pattern is formed by a conventional lithographicprocess, as will be understood by one of ordinary skill in the art. Thecapacitor masking pattern 325 generally exposes a capacitor region 326of the first ILD layer 320 residing over the bottom plate 314, whilecovering the remainder of the semiconductor substrate 301 withphotoresist. Subsequently, the first ILD layer 320 is etched in thecapacitor region 326 in act 235 of FIG. 2A.

FIG. 7 illustrates the results of etching the first ILD layer 320 usingthe capacitor masking pattern 325 as a mask, and using the silicidelayer 315 as an etch stop in the capacitor region 326. The etch processperformed in act 235 of FIG. 2A, for example, comprises an anisotropicdry etching process which can be performed to expose the silicide layer315 over the bottom plate 314 in the capacitor region 326. Following theetching of the first ILD layer 320, the mask 325 is removed byconventional processes, such as ashing.

In act 240 of FIG. 2A, a thin dielectric is formed over thesemiconductor substrate. FIG. 8 illustrates the thin dielectric 330(e.g., a thin oxide) overlying the first ILD layer 320 and the silicidelayer 315 which has been exposed in the capacitor region 326. Formingthe thin dielectric 330 defines a capacitor dielectric 331 in thecapacitor region 326, and also protects a subsequently deposited metallayer (not shown) from diffusion of gases from the first ILD layer 320,as will be described hereafter. The thin dielectric 330 is formed, forexample, by a Low Pressure Chemical Vapor Deposition (LPCVD) process toa thickness of between 200 Å to 1000 Å, depending on capacitance andvoltage coefficient requirements. Smaller thicknesses of the thindielectric 330 result in a relatively high capacitance per unit area, asis typically preferred in analog applications. However, smallerthicknesses (less than 200 Å) of the thin dielectric 330 may also resultin relatively higher voltage coefficients, which are not typicallydesirable in analog applications.

Forming the thin dielectric 330 by LPCVD processing is advantageousbecause LPCVD processing forms a generally uniform thickness of the thindielectric 330, which is especially important in the capacitor region326 to maintain a low hysteresis of the capacitor (not shown). Othermethods of forming the thin dielectric 330 such as PECVD, APCVD, orother processing, however, are contemplated as falling within the scopeof the present invention. According to one exemplary aspect of thepresent invention, a titanium nitride (TiN) layer (not shown) is formedover the thin dielectric 330 to further protect the thin dielectric 330from subsequent planarization, as will be described hereafter.

Following the formation of the thin dielectric 330 in act 240 of FIG.2A, a contact masking pattern is formed in act 245. FIG. 9 illustrates acontact masking pattern 335 which has been formed by conventionalphotolithographic processing. The contact masking pattern 335 comprisesone or more contact holes 340 which expose the thin dielectric 330,while the remainder of the semiconductor substrate 301 is covered by thecontact masking pattern. Subsequently, in act 250 of FIG. 2A, an etchprocess is performed using the contact masking pattern 335 of FIG. 9 asa mask, and the silicide 315 as an etch stop. FIG. 10 illustrates theresults of performing act 250, wherein the thin dielectric 330 and thefirst ILD layer 320 have been etched through the contact holes 340 inthe contact masking pattern 335. According to one exemplary aspect ofthe present invention, a cleaning process is performed after the etchprocess of act 250 of FIG. 2A in order to remove any remaining etchbyproducts.

According to another exemplary aspect of the present invention, the etchprocess performed in act 250 etches the thin dielectric 330 and thefirst ILD layer 320 underlying the contact holes 340 in the contactmasking pattern 335 to form a bottom plate contact hole 350 and a moatcontact hole 352, as illustrated in FIG. 10. Accordingly, the etchprocess of act 250 utilizes the silicide layer 315 as an etch stop informing the bottom plate contract hole 350, and utilizes a moat 354 asan etch stop in forming the moat contact hole 352. The moat 354, forexample, is a heavily doped region of the semiconductor substrate 301which permits the application of specific electrical potentials such asground potential or V_(SS) to devices formed on the substrate. It shouldbe noted that the etch process performed in act 250 of FIG. 2A does notsuffer the deleterious effects of etching a TiN layer as described inthe aforementioned prior art.

In conventional processing, a dry TiN etch is used in order to yieldstraight TiN layer profiles. However, a significant drawback to a dryTiN etch is a low etch selectivity of TiN-to-poly or TiN-to-silicon. Ifa dry over-etch is optimized for removing TiN “stringers” (e.g., TiNwhich remains along the edges of the poly 310 or field oxide 305), theetch starts pitting into the semiconductor surface 301, thereby causingdiode leakage problems. One solution is to convert all or part of thedry etch into a wet etch, as the wet etch removes TiN stringers morereadily without damaging semiconductor surface 301. However, a wet etchmay deleteriously undercut the TiN layer and dielectric layers (e.g.,capacitor edges). This, in turn, degrades capacitor matchingperformance, which is a key requirement for capacitors used in analogcircuit applications.

Following the etching process performed in act 250 of FIG. 2A, a metallayer is deposited over the semiconductor substrate in act 255. FIG. 11illustrates a metal layer 355 which has been formed over thesemiconductor substrate 301. The metal layer 355 comprises, for example,tungsten, wherein the metal layer generally fills the bottom platecontact hole 350, the moat contact hole 352, and the capacitor region326. Subsequently, the metal is planarized in act 260 of FIG. 2A toremove a portion of the metal layer 355. As illustrated in FIG. 12, theplanarization performed in act 260 is performed to electrically isolatethe capacitor 360, and to furthermore define a top plate 361 of thecapacitor, a bottom plate connector 362, and a moat connector 363.Furthermore, electrical connection regions 365 to the top plate 361,bottom plate connector 362, and moat connector 363 are defined by theplanarization performed in act 260. According to one aspect of theinvention, the metal layer 355 advantageously provides low voltagecoefficients in the capacitor 360 due to being a metal such as tungsten.

The planarization furthermore electrically isolates the capacitor 360from other devices (not shown) on the semiconductor substrate 301.According to another exemplary aspect of the present invention, abarrier metal (not shown) such as titanium and/or titanium nitride isformed prior to depositing the metal layer in act 255 of FIG. 2A.Furthermore, the barrier metal (not shown) is also planarized along withthe metal layer deposited in act 255. According to yet another exemplaryaspect of the invention, a conductive connecting layer 370, asillustrated in FIG. 13, can be formed and patterned over the electricalconnection regions 365 in order to connect the capacitor 360 to otherdevices (not shown) on the semiconductor substrate 301.

Although the invention has been shown and described with respect tocertain aspects, equivalent alterations and modifications will occur toothers skilled in the art upon the reading and understanding of thisspecification and the annexed drawings. In particular regard to thevarious functions performed by the above described components (systems,devices, assemblies, etc.), the terms used to describe such componentsare intended to correspond, unless otherwise indicated, to any componentwhich performs the specified function of the described component (i.e.,that is functionally equivalent), even though not structurallyequivalent to the disclosed structure that performs the function in theherein illustrated exemplary aspects of the invention. In addition,while a particular feature of the invention may have been disclosed withrespect to only one of several aspects, such feature may be combinedwith one or more other features of the other aspects as may be desiredand advantageous for any given or particular application. Furthermore,to the extent that the term “includes” is used in either the detaileddescription and the claims, such term is intended to be inclusive in amanner similar to the term “comprising.”

What is claimed is:
 1. A method for forming a high precision analogcapacitor on a semiconductor substrate, the method comprising: forming afield oxide layer over a portion of the substrate; forming a polysiliconlayer over the field oxide layer; forming a silicide over thepolysilicon layer, thereby defining a bottom plate of the capacitor;forming a first interlayer dielectric over the substrate; forming acapacitor masking pattern over the substrate; etching the firstinterlayer dielectric using the capacitor masking pattern as a mask andthe silicide as an etch stop, thereby defining a capacitor region;forming a thin dielectric over the substrate; forming a contact maskingpattern over the substrate; etching the thin dielectric and the firstinterlayer dielectric using the contact masking pattern as a mask andthe silicide as an etch stop to form a bottom plate contact hole;depositing a metal over the substrate, thereby filling the capacitorregion and the bottom plate contact hole; and planarizing the metal,wherein a top plate of the capacitor and an electrical connection to thebottom plate of the capacitor are defined, and wherein the top plate ofthe capacitor and the electrical connection to the bottom plate of thecapacitor are laterally isolated by the first interlayer dielectric. 2.The method of claim 1, wherein forming a first interlayer dielectricover the substrate comprises: depositing a first undoped silicate glasslayer over the substrate; depositing a phosphosilicate glass layer overthe substrate; densifying the first undoped silicate glass layer and thephosphosilicate glass layer; and planarizing the phosphosilicate glasslayer.
 3. The method of claim 2, further comprising depositing a secondundoped silicate glass layer over the planarized phosphosilicate glasslayer.
 4. The method of claim 1, further comprising planarizing thefirst interlayer dielectric.
 5. The method of claim 4, wherein the actof planarizing the first interlayer dielectric comprises chemicalmechanical polishing.
 6. The method of claim 1, wherein the act offorming a first interlayer dielectric over the substrate comprisesforming a tetraethyl-orthosilicate (TEOS) layer to a thickness of about10 KÅ.
 7. The method of claim 1, wherein the thin dielectric comprises athin oxide.
 8. The method of claim 1, wherein forming the thindielectric over the substrate comprises a low pressure chemical vapordeposition (LPCVD) process to form the thin dielectric to a thickness ofbetween 200 Å and 1000Å.
 9. The method of claim 1, further comprisingcleaning the substrate after etching the thin dielectric and the firstinterlayer dielectric layer.
 10. The method of claim 1, furthercomprising forming a barrier metal layer over the substrate prior todepositing the metal layer.
 11. The method of claim 10, wherein thebarrier metal layer comprises titanium nitride or titanium tungsten. 12.The method of claim 1, further comprising: depositing a first wiringlayer over the substrate; forming a first wiring layer masking pattern;and etching the first wiring layer using the first wiring layer maskingpattern as a mask and the thin dielectric layer as an etch stop.
 13. Themethod of claim 1, wherein the metal layer comprises tungsten.
 14. Themethod of claim 1, wherein the act of planarizing the metal layercomprises chemical mechanical polishing.
 15. The method of claim 1,further comprising forming a titanium nitride layer or a titaniumtungsten layer over the thin dielectric layer, and wherein etching thethin dielectric and the first interlayer dielectric using the contactmasking pattern as a mask further comprises etching the respectivetitanium nitride layer or titanium tungsten layer.
 16. The method ofclaim 1, wherein etching the thin dielectric and the first interlayerdielectric further comprises forming a moat contact hole by using thecontact masking pattern as a mask and a moat as an etch stop.
 17. Themethod of claim 16, wherein depositing a metal over the substratefurther comprises filling the moat contact hole.
 18. The method of claim17, wherein planarizing the metal further comprises defining anelectrical connection to the moat, and wherein the top plate of thecapacitor and the electrical connection to the bottom plate of thecapacitor and the electrical connection to the moat are laterallyisolated by the first interlayer dielectric.
 19. A method for forming ahigh precision analog capacitor on a semiconductor substrate, the methodcomprising: forming a field oxide layer over a portion of the substrate;forming a polysilicon layer over the field oxide layer; forming asilicide over the polysilicon layer, thereby defining a bottom plate ofthe capacitor; depositing undoped silicate glass over the substrate;depositing phosphosilicate glass over the substrate; densifying theundoped silicate glass and the phosphosilicate glass; planarizing thephosphosilicate glass; depositing undoped silicate glass over theplanarized phosphosilicate glass; forming a capacitor masking patternover the substrate; etching the undoped silicate glass andphosphosilicate glass using the capacitor masking pattern as a mask andthe suicide as an etch stop, thereby defining a capacitor region;forming a thin dielectric over the substrate; forming a contact maskingpattern over the substrate; etching the thin dielectric, undopedsilicate glass and phosphosilicate glass using the contact maskingpattern as a mask and the silicide as an etch stop to form a bottomplate contact hole; depositing a metal over the substrate, therebyfilling the capacitor region and the bottom plate contact hole; andplanarizing the metal, wherein a top plate of the capacitor and anelectrical connection to the bottom plate of the capacitor are defined,and wherein the top plate of the capacitor and the electrical connectionto the bottom plate of the capacitor are laterally isolated by theundoped silicate glass and phosphosilicate glass.
 20. The method ofclaim 19, wherein the act of depositing undoped silicate glass over thesubstrate comprises depositing a tetraethyl-orthosilicate (TEOS) layerto a thickness of about 10 KÅ.
 21. The method of claim 19, wherein thethin dielectric comprises a thin oxide.
 22. The method of claim 19,wherein forming the thin dielectric over the substrate comprises lowpressure chemical vapor deposition (LPCVD) processing forming the thindielectric to a thickness of between 200 Å and 1000Å.
 23. The method ofclaim 19, further comprising cleaning the substrate after etching thethin dielectric, undoped silicate glass and phosphosilicate glass. 24.The method of claim 19, further comprising forming a barrier metal layerover the substrate prior to depositing the metal layer.
 25. The methodof claim 24, wherein the barrier metal layer comprises titanium nitrideor titanium tungsten.
 26. The method of claim 19, further comprising:depositing a first wiring layer over the substrate; forming a firstwiring layer masking pattern; and etching the first wiring layer usingthe first wiring layer masking pattern as a mask and the thin dielectriclayer as an etch stop.
 27. The method of claim 19, wherein the act ofplanarizing the phosphosilicate glass comprises chemical mechanicalpolishing.
 28. The method of claim 19, wherein the metal layer comprisestungsten.
 29. The method of claim 19, wherein the act of planarizing themetal layer comprises chemical mechanical polishing.
 30. The method ofclaim 19, further comprising forming a titanium nitride layer or atitanium tungsten layer over the thin dielectric layer, and whereinetching the thin dielectric, undoped silicate glass and phosphosilicateglass using the contact masking pattern as a mask further comprisesetching the respective titanium nitride layer or titanium tungstenlayer.
 31. The method of claim 19, wherein etching the thin dielectricand the first interlayer dielectric further comprises forming a moatcontact hole by using the contact masking pattern as a mask and a moatas an etch stop.
 32. The method of claim 31, wherein depositing a metalover the substrate further comprises filling the moat contact hole. 33.The method of claim 32, wherein planarizing the metal further comprisesdefining an electrical connection to the moat, and wherein the top plateof the capacitor and the electrical connection to the bottom plate ofthe capacitor and the electrical connection to the moat are laterallyisolated by the first interlayer dielectric.